Most of these ingredients can be found in Asian food stores and some specialty grocery stores. Kombu is a dark green long thick sea vegetable from the kelp family. Used frequently in Japanese cooking, it is an essential ingredient of dashi, a flavorful stock.

Clean the kombu by wiping it with a damp cloth. Place the kombu and ginger in a stockpot with 5 cups of cold water and heat over medium heat. Just before the water boils, remove the pot from the heat. Watch carefully you don't want the water to boil or the dashi will become too strongly flavored.

Allow the mixture to stand for 5 minutes, remove the kombu, and return the pot to medium heat. When the broth once again nears the boiling point, remove the pot from the heat and add the bonito flakes. When the flakes sink to the bottom of the pot, strain the dashi through cheesecloth or a fine-mesh strainer.

Measure out 4 cups of dashi broth. In a medium saucepan, bring the broth to a simmer over medium heat. Submerge a small strainer halfway into the broth, add the miso to the broth within the strainer, and whisk to combine the miso and broth. Taste and add more miso, 1 tablespoon at a time, if you want a deeper flavor.

Remove the strainer and add the chicken. Simmer until chicken is cooked through, about 2 minutes. Add noodles and heat through. Ladle the soup into bowls, garnish with scallion greens and serve.